We don't pronounce the very last consonants of a word as they should be in English. For example: "nước" is pronounced as /'nʊək/ without the /kə.../ sound at the end of it.

Try saying /nʊək/ then stop immediately when you reach the end of the word. Don't make the extra /kə.../ sound which is like you are gargling or clearing your throat. The same rule applies to most of the last consonants of any other words. This makes "uống nước" sound like "uốnước" /'uon'ʊək/ without the /kə.../ sound at the end of it.